"Protection from Demons and from Dragons" means the following:
-- Baneslayer Angel can't be blocked by creatures with the creature type Demon or the creature type Dragon.
-- Baneslayer Angel can't be targeted abilities from sources with the creature type Demon or the creature type Dragon, or by spells with either of those types.
-- All damage that would be dealt to Baneslayer Angel by sources with the creature type Demon or the creature type Dragon is prevented.
-- Baneslayer Angel can't be enchanted by Auras or equipped by artifacts that have somehow gotten the creature type Demon or the creature type Dragon.